CN87103057A

CN87103057A - Gypsum calcining method and its equipment

Info

Publication number: CN87103057A
Application number: CN 87103057
Authority: CN
Inventors: 李培基; 杨景华; 顾洪深
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-11-21
Filing date: 1987-11-21
Publication date: 1988-05-18

Abstract

In order to overcome the shortcomings of low productivity, poor working conditions or large equipment investment in the existing gypsum production technology, the present invention changes the traditional "crushing, crushing, and drying" process flow, and provides a method for calcining gypsum (the process flow is: "Crushing, drying, crushing") and special equipment designed to realize this method: vertical landslide calcining kiln. The temperature in the kiln can be controlled at 100°C to 1100°C as required, or the gypsum block can be dried or heated to dehydrate or calcined, and the obtained block can be ground into a product by grinding equipment.

Description

Gypsum calcining method and equipment thereof

The invention relates to a gypsum calcining method and equipment thereof, in particular to a method for calcining gypsum in a vertical landslide calcining kiln or drying an alpha-type semi-hydrated gypsum block or heating and dehydrating natural dihydrate gypsum or industrial waste gypsum material balls into a beta-type gypsum block or calcining natural dihydrate gypsum or natural anhydrite or industrial waste gypsum material balls into an I-type anhydrous gypsum or floor gypsum block and then grinding the gypsum block into gypsum powder by using grinding equipment.

The raw materials for producing the gypsum product are mainly natural dihydrate gypsum and can also be natural anhydrous gypsum. The present general process at home and abroad is that the dihydrate gypsum raw material is firstly crushed into particles with the particle size of less than 10 cm by a crusher, and then the dihydrate gypsum is crushed in a pulverizer. The crushed powder is heated and dehydrated in an iron frying pan, and the gypsum powder is uniformly heated by continuously stirring during heating. When the dihydrate gypsum is ground in a common ball mill, the local temperature can reach more than 120 ℃ due to the impact of steel balls, the dihydrate gypsum loses water at more than 107 ℃, at the moment, the grinding efficiency is reduced due to the fact that part of dihydrate gypsum is broken, and a large domestic factory does not use a ball mill but uses a Raymond mill with a blast device. However, Raymond mill is expensive and not easy to popularize. On the other hand, in China, due to condition limitation, iron frying pans are produced discontinuously, discharging is carried out after one pan is fried, and then raw materials are added for frying. The gypsum is heated in the pan to discharge a large amount of water, and is in a boiling state, and a large amount of dust is sprayed out. Therefore, the heat efficiency is low, the production efficiency is also low, and meanwhile, the dust is extremely large, the labor condition is poor, and the health of workers is influenced. Although the automatic closed frying pan applied abroad can continuously feed and discharge materials, the yield is not high, the thermal efficiency is low and the price is high, as described in the US 4113836. As for the anhydrous gypsum cementing material prepared by calcining dihydrate gypsum or natural anhydrite at the high temperature of 700-1000 ℃, the calcining tool commonly used at home and abroad is known as a rotary kiln, but the combustion consumption is high, the thermal efficiency is low, and the equipment investment is also large.

The invention aims to overcome the defects of low productivity, poor labor condition or large equipment investment in the gypsum production, change the traditional process flow of crushing → grinding → drying, and provide a method for calcining gypsum (the process flow is crushing → drying → crushing) and special equipment designed for realizing the method: a vertical landslide calcining kiln.

The invention is realized by the following steps: alpha gypsum blocks or natural dihydrate gypsum or natural anhydrous gypsum ore which are treated by pressure of about 2 kilograms and contain free water are crushed to be less than 4 centimeters by a jaw crusher or a hammer crusher or industrial waste gypsum is made into material balls with the diameter of less than 4 centimeters, and then the material balls are processed by a vertical landslide calcining kiln or dried or heated to be dehydrated or calcined into gypsum blocks and then are ground by a grinding device: pulverizing into calcined gypsum powder by common ball mill or Raymond mill.

The temperature of the vertical landslide calcining kiln is controlled to be about 100 ℃, alpha gypsum blocks which are treated by pressure of about 2 kilograms and contain free water are dried, and then the alpha gypsum blocks are ground into alpha gypsum powder by a grinding device.

Controlling the temperature of a vertical landslide calcining kiln to be about 140 ℃, heating and dehydrating natural dihydrate gypsum or industrial waste gypsum pellets into a beta-type hemihydrate gypsum material block, and then grinding into beta-type gypsum powder by using grinding equipment.

Controlling the temperature of a vertical landslide calcining kiln at 700-1000 ℃, calcining natural dihydrate gypsum or natural anhydrite or industrial waste gypsum material balls into I-shaped anhydrous gypsum or floor gypsum blocks, and then grinding the gypsum blocks into gypsum powder by using grinding equipment.

The vertical slide calcining kiln is composed of a chimney, a charging hopper, a discharging port, a combustion chamber, a slide and the like, wherein the slide has 4-5 layers and is composed of a slide frame and slide strips, and the included angle between the slide frame and the slide strips is 5-50 degrees. The slope inclination angle of the slide is 30-50 degrees. The landslide inclination angle may be adjusted by means of an adjustment bracket. The slide frame and the slide strips are made of common cast iron or heat-resistant cast iron or high-temperature-resistant metal and the like. The temperature can be determined according to the use temperature, and when the temperature in the kiln is less than 400 ℃, the slide frame and the slide strips are made of common cast iron. When the temperature in the kiln is less than 900 ℃, the slide frame and the slide strips are made of heat-resistant cast iron. When the temperature in the kiln is more than 900-1100 ℃, the slide frame and the slide strip are made of high-temperature resistant metal. Because the vertical landslide calcining kiln uses a combustion chamber of a semi-gas combustion method or a combustion chamber of a direct-fired combustion method or a fluidized bed furnace and other combustion kilns as combustion chambers, the temperature in the kiln can be controlled to be 100-1100 ℃ as required. The method can be used for drying and dehydrating alpha semi-hydrated gypsum which is treated by about 2 kilograms of pressure and contains free water, can be used for producing beta semi-hydrated gypsum by heating and dehydrating dihydrate gypsum or industrial waste gypsum pellets, and can also be used for calcining I type anhydrous gypsum or floor gypsum at the high temperature of 700-1000 ℃. Adding coarsely crushed natural dihydrate gypsum or natural anhydrous gypsum ore particles with the diameter of about 4 cm or industrial waste gypsum pellets with the diameter of less than 4 cm or alpha gypsum blocks containing free water after being subjected to pressure treatment of about 2 kilograms into a feeding hopper of a vertical landslide calcining kiln, wherein the blocks are distributed on a slide into a thin layer and slide down from the surface of the slide slowly, hot air from a combustion chamber penetrates through a gap space between slide strips from the lower part to heat the blocks, and the blocks are heated by the hot air for 4-5 times when passing through 4-5 layers of slides. And when the material is transferred from the upper layer slide to the next layer slide, the material is just turned over. The material blocks on the upper part do not slide down when the bottom does not discharge, and the whole discharging time is completely controllable (the quantity of discharged materials on the bottom and the quantity of automatically added materials on the upper part). The kiln bottom is provided with two combustion chambers, and can be of a direct-fired type, a semi-gas type or a fluidized bed furnace type. The temperature in the kiln is required to be 100-1100 ℃, the temperature can be controlled by a combustion chamber, and forced ventilation can be considered when the high temperature is required. The dried alpha-type semi-hydrated gypsum blocks or the heated and dehydrated beta-type semi-hydrated gypsum blocks or the calcined I-type anhydrous gypsum or floor gypsum blocks can be ground into the calcined gypsum powder by using a common ball mill.

Compared with the prior art, the invention has the following advantages:

1. energy conservation in a large scale:

the method is characterized in that hot air is directly used for heating in a vertical landslide calcining kiln, and the gypsum powder is heated for 4-5 times along 4-5 layers of slides, so that the preheating and dehydration processes are completed in the kiln, the continuous production can be realized, and the heat efficiency is relatively improved.

The traditional method is to grind the dihydrate gypsum blocks and then stir-fry the dihydrate gypsum blocks into powder, and the dihydrate gypsum powder is put into a ball mill and has the molecular weight of 344.34. The method of the invention is to dehydrate and then grind, and when the gypsum is put into a ball mill, the gypsum is a beta-type semi-hydrated gypsum block, and the molecular weight is 290.28. Compared with the traditional method, the grinding amount is reduced by 15.7 percent, so the energy consumption of the ball mill can be reduced by more than 15.7 percent.

2. The production efficiency is improved:

the traditional method uses an iron pan for processing, has intermittent production, consumes more time and has low production efficiency, which is the weakest link of the processing and the production of the plaster of paris. The method of the invention removes the iron pan, changes the vertical landslide calcining kiln into the iron pan, has the thermal efficiency of 60 percent, can continuously produce and has high speed. And the yield can be greatly improved because the grindability of the raw materials is improved.

② when the material block is the plaster of paris when the material block is put into the ball mill by the method of the invention, the quantity of the plaster of paris is reduced by 15.7 percent compared with the quantity of the plaster of paris when the material block is put into the ball mill by the old method, thus the efficiency of the plaster of paris produced finally can be improved by more than 15.7 percent.

The gypsum blocks are put into the mill, so that no water is separated out during grinding, the efficiency of the mill can be improved, and the common ball mill with low price can be used.

3. The method reduces dust, improves the working conditions of workers, and protects the health of the workers and the environmental sanitation.

4. The process and the equipment are simplified, the investment is reduced, and the economic benefit is improved.

The specific structure of the apparatus of the present invention is given by example 1 and its drawings.

Fig. 1 is a sectional view of a vertical landslide calcining kiln according to the present invention.

Figure 2 is a front view of a vertical slide for a landslide calciner according to the present invention.

Fig. 3 is a top view of a vertical slide for a landslide calciner according to the present invention.

Example 1

The vertical slide calcining kiln is composed of a chimney, a charging hopper, a discharging port, a combustion chamber, a slide (1) and the like, wherein the slide (1) has 4-5 layers and is composed of a slide frame (2) and slide strips (3), and the included angle alpha of the slide frame (2) and the slide strips (3)₂Is 5-50 degrees. Slide slope inclination angle alpha of slide (1)₁Is 30-50 degrees. Slope inclination angle alpha₁Can be adjusted by means of an adjustment bracket. The slide frame (2) and the slide strips (3) are made of common cast iron or heat-resistant cast iron or high-temperature-resistant metal and the like. Because the vertical landslide calcining kiln uses a combustion chamber of a semi-gas combustion method or a combustion chamber of a direct-fired combustion method or a fluidized bed furnace and other combustion kilns as combustion chambers, the temperature in the kiln can be controlled to be 100-1100 ℃ as required. Forced ventilation may be considered when high temperatures are required. The material blocks to be dried or heated for dehydration or calcination are added into a charging hopper, the material blocks slide down from the surface of a slide (1), hot air from a combustion chamber penetrates through the gap space between slide strips (3) from the lower part to heat the material, and the material blocks are heated by the hot air for 4-5 times when passing through 4-5 layers of slides (1). And when the material block is transferred from the upper layer slide (1) to the lower layer slide (1), the material block is just turned over. The bottom does not discharge, the upper material does not slide down any more, and the whole discharging time is completely controllable (the bottom discharges the material, and the upper material is automatically added).

The specific process of the present invention is given in examples 2, 3, 4 and 5.

Example 2: drying and dehydrating the alpha gypsum containing free water

Adding alpha gypsum blocks which are treated by less than 2 atmospheric pressures at the temperature of 140 ℃ and contain a large amount of free water into a charging hopper of a vertical landslide calcining kiln, controlling the temperature in the kiln to be less than 100 ℃ according to the process flow of the embodiment 1, drying the alpha semi-hydrated gypsum blocks, and grinding the dried blocks by using a common ball mill to obtain the alpha semi-hydrated gypsum powder.

Example 3: examples of Industrial waste Gypsum materials

Most of free water is removed from the industrial waste gypsum material by a filter press, the water content is reduced to below 8 percent, the gypsum is pelletized, the diameter of the pellets is reduced to below 4 cm, the pellets are added into a charging hopper of a vertical landslide calcining kiln, the temperature in the kiln is controlled to be about 140 ℃ according to the process flow of the embodiment 1, and the beta-type semi-hydrated gypsum material block can be prepared by heating and dehydration. When the temperature in the kiln is controlled between 700 ℃ and 1000 ℃, the I-type anhydrous gypsum or floor gypsum block is calcined. The material block is directly put into a common ball mill to be ground into a finished product.

Example 4: examples of Natural dihydrate Gypsum

Crushing natural dihydrate gypsum ore into blocks with the particle size of less than 4 cm by using a jaw crusher, adding the blocks into a feeding hopper of a vertical landslide calcining kiln, controlling the temperature in the kiln to be about 140 ℃ according to the process flow of the embodiment 1, and heating and dehydrating to obtain the beta-type hemihydrate gypsum blocks. When the temperature in the kiln is controlled to be 700-1000 ℃, the I-type anhydrous gypsum or floor gypsum block is obtained. The material blocks are ground into finished products in a common ball mill.

Example 5: examples for natural anhydrite.

Crushing natural anhydrite into blocks with the grain diameter of less than 4 cm by using a jaw crusher, adding the blocks into a charging hopper of a vertical landslide calcining kiln, and calcining the blocks at the temperature of 700-1000 ℃ in the kiln according to the process flow of the embodiment 1 to obtain the floor gypsum blocks. The material blocks are ground into finished products in a common ball mill.

Claims

1. A method for producing gypsum, which is characterized in that α gypsum block or natural dihydrate gypsum or natural anhydrous gypsum ore containing free water after pressure treatment of about 2 kg is crushed to less than 4 cm or industrial After the waste gypsum is made into balls with a diameter of less than 4 cm, it is passed through a vertical landslide calcining kiln or dried or heated for dehydration or calcined into gypsum blocks, and then crushed into gypsum powder by grinding equipment.

2. The method for producing gypsum according to claim 1, characterized in that the temperature of the vertical landslide calcining kiln is controlled at about 100°C, and the α-gypsum block containing free water after pressure treatment of about 2 kg is dried, and then Grind it into α gypsum powder with grinding equipment.

3. The method for producing gypsum according to claim 1, characterized in that the temperature of the vertical landslide calcining kiln is controlled at about 140°C, and natural dihydrate gypsum or industrial waste gypsum balls are heated and dehydrated into β-type gypsum blocks, Then use grinding equipment to grind into β gypsum powder.

4. The method for producing gypsum according to claim 1, characterized in that the temperature of the vertical landslide calcining kiln is controlled at 700°C to 1000°C, and natural dihydrate gypsum or natural anhydrite or industrial waste gypsum balls are calcined into I Anhydrous gypsum or floor gypsum blocks are then ground into gypsum powder with grinding equipment.

5. A vertical landslide calcining kiln for drying or heating dehydration or calcining gypsum ore or gypsum material balls according to claim 1, which is composed of a chimney, a hopper, a discharge port, a combustion chamber and a slide [1 ], etc., it is characterized in that the slide (1) has 4 to 5 layers, is composed of a slide frame (2) and a slide bar (3), and the angle α between the slide frame (2) and the slide bar (3) ₂ is 5-50.

6. The vertical landslide calcining kiln according to claim 5, characterized in that the slope angle α ₁ of the slide (1) is 30-50.

7. The vertical landslide calcining kiln according to claim 5, characterized in that it has an adjustment bracket for adjusting the slope angle _α1 of the slide (1).

8. The vertical landslide calcining kiln according to claim 5, characterized in that the slide frame (2) and slide bar (3) are made of ordinary cast iron or heat-resistant cast iron or high-temperature resistant metal.